Working apparatus, in particular excavator or machine for material handling

ABSTRACT

The present disclosure shows a working apparatus, in particular an excavator or a machine for material handling, having an element movable via at least one hydraulic working cylinder, wherein at least one energy recovery cylinder is provided for recovering energy from the movement of the movable element, said energy recovering cylinder being filled with gas at the base side and having an annular space filled with a medium. In this respect, a flow restricting element is provided which restricts the flow of the medium from the annular space on a sudden moving out of the piston rod.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 102011 106 260.6, entitled “Working apparatus, in particular excavator ormachine for material handling”, filed May 18, 2011, which is herebyincorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

The present disclosure relates to a working apparatus, in particular toan excavator or to a machine for material handling, having an elementmovable via at least one hydraulic working cylinder, wherein at leastone energy recovery cylinder is provided for recovering energy from themovement of the movable element, said energy recovery cylinder beingfilled with gas at the base side and having an annular space filled witha medium.

Such a working apparatus is known from DE 10 2008 034 582 A1 whosecontent is made the subject of the present application in full. Theenergy recovery cylinder is in this respect used, e.g., to store thepotential energy on a downward movement of the movable element bycompressing the gas in the base side filled with gas which is then againavailable to support the upward movement again. In the loaded state ofthe energy recovery cylinder, large amounts of energy are usually storedin the compressed gas in this respect.

BACKGROUND AND SUMMARY

It is the object of the present disclosure to make the operation of aworking apparatus such as described above more reliable.

This object is achieved in accordance with the present disclosure by aworking apparatus which has an element movable via at least onehydraulic working cylinder, wherein at least one energy recoverycylinder is provided for recovering energy from the movement of themovable element, said energy recovery cylinder being filled with gas atthe base side and having an annular space filled with a medium.Provision is made in accordance with the present disclosure in thisrespect so that a flow restricting element is provided which restrictsthe flow of the medium from the annular space on a sudden moving out ofthe piston rod. The present disclosure is in this respect usedparticularly advantageously in an excavator or in a machine for materialhandling, in particular in such a machine in which a boom or armpivotable about a horizontal axis forms the movable element.

The inventors of the present disclosure have recognized in this respectthat the high amount of energy which is stored in an energy recoverycylinder in the loaded state can become a safety risk if there is forany reason a defect at the bearing points, the bearing parts of theenergy recovery cylinder, or the equipment. To prevent a moving out ofthe piston rod of the energy recovery cylinder at an uncontrolled speedin the event of such a failure of the bearing points or securing pointsin which the piston rod is no longer mechanically secured, the flowrestriction element is provided in accordance with the presentdisclosure which restricts the flow of the medium out of the annularspace on such a sudden defect. The speed at which the piston rod of theenergy recovery cylinder is moved out is hereby simultaneouslycontrolled. Damage to the energy recovery cylinder, to the workingapparatus, and to persons can hereby be prevented.

For this purpose, in a first embodiment, the annular space can be incommunication via the flow restriction element with an externalreservoir in which the medium flows on the moving out of the piston rod.In this respect, in particular an additional container is installed asan external reservoir at the energy recovery cylinder and receives themedium on the moving out of the piston rod and makes the mediumavailable for filling the annular space on the moving in of the pistonrod.

In this respect, a medium may be used in the present disclosure which isnot compressible. In particular hydraulic oil may be used. The expansionof the energy recovery cylinder can thus be controlled via the flowspeed of the non-compressible medium.

A restrictor or diaphragm is advantageously used as the flow restrictionelement. It is advantageously adjustable so that the flow speed can beset via the restrictor or diaphragm.

A valve unit, in particular a valve unit with an adjustable volume flow,can equally be used as the flow restriction element. A flow controlvalve or a burst pipe protection can be used for this purpose, forexample.

In an alternative embodiment of the present disclosure, the annularspace can be in communication via the flow restriction element with thebase side of the energy recovery cylinder filled with gas. A gasexchange must thus take place between the annular space and the baseside via the flow restriction element to move out the piston rod,whereby the outward movement speed can likewise be controlled.

In this respect, the flow restriction element is advantageously arestrictor. In this respect, a check valve can advantageously bearranged parallel to the restrictor so that the gas flow between thebase side and the annular space is not restricted by the restrictor onthe inward movement of the piston rod.

In a possible application of the present disclosure, the flowrestriction element restricts the flow of the medium out of the annularspace independently of the remaining control of the working apparatusand is in particular independent of the control which controls themovement of the movable element.

Furthermore, the flow restriction element can be a passive element, i.e.an element which can be controlled via a control. The flow restrictionelement thus solely serves the purpose of securing the energy recoverycylinder in the case of damage. A particularly simple and inexpensivedesign is hereby made possible.

The present disclosure is in particular used in those working apparatusin which the energy recovery cylinder has a hollow piston rod. Theworking apparatus and the energy recovery cylinder are in this respectadvantageously set up as is shown in DE 10 2008 034 582 A1, which isincorporated by reference herein as one example configuration for theworking cylinder and energy recovery cylinder of the present disclosure.

Further advantageously, the working device is in this respect a movableworking apparatus, in particular an excavator or a machine for materialhandling. This working apparatus has an element which is movable via atleast one hydraulic working cylinder, wherein the energy recoverycylinder serves the energy recovery from the movement of the movingelement.

The movable element of the working apparatus in accordance with thepresent disclosure is advantageously pivotally connected to the workingapparatus pivotable about a vertical axis of rotation and is pivotablein a vertical pivoting plane via the hydraulic working cylinder orcylinders. The movable element can in this respect, in particular, bethe arm of an excavator or the boom of a machine for material handling.Further advantageously, the movable working apparatus has anundercarriage with traveling gear and a superstructure arrangedrotatably about a vertical axis of rotation thereon to which the movableelement is pivotally connected.

In this respect, a piece of working equipment, for example a shovel or agrip, can be arranged at the movable element. On the lowering of themovable element, the potential energy of the movable element and of thepiece of working equipment is stored via the energy recovery cylinder inorder to at least partly compensate the equipment weight on the upwardmovement of the movable element. Less energy therefore has to be exertedvia the hydraulic working cylinders to move the movable elementupwardly.

The energy recovery cylinder in accordance with the present disclosureis in this respect advantageously arranged like the hydraulic workingcylinder or cylinders between the superstructure of the workingapparatus and the movable element. The energy recovery cylinder thusmoves parallel with the hydraulic working cylinder on a movement of themovable element. The working apparatus can be designed as is shown inmore detail in DE 10 2008 034 582 A1.

In addition to the working apparatus, the present disclosure furthermoreincludes an energy recovery cylinder for a working apparatus asdescribed above. The energy recovery cylinder is in this respect filledwith gas at the base side and has an annular space filled with a medium,wherein a flow restriction element is provided which restricts the flowof the medium out of the annular space on a sudden moving out of thepiston rod. The energy recovery cylinder is in this respectadvantageously designed as described above.

The present disclosure further relates to a method of operating aworking apparatus, in particular an excavator or a machine for materialhandling, having an element movable via at least one hydraulic workingcylinder, wherein at least one energy recovery cylinder is provided forrecovering energy from the movement of the movable element, said energyrecovery cylinder being filled with gas at the base side and having anannular space filled with a medium. In accordance with the presentdisclosure, the method in this respect provides that the flow of themedium out of the annular space is restricted on an unwanted moving outof the piston rod. In this respect, in particular the flow of the mediumout of the annular space is restricted when the piston rod is no longermechanically secured due to a defect at the bearing points or at thebearing parts of the energy recovery cylinder or of the workingapparatus so that the energy stored in the energy recovery cylinderwould result in an uncontrolled moving out of the piston rod. The movingout of the piston rod is therefore also controlled by the inventiverestriction of the flow of the medium out of the annular space in caseof damage so that damage to the component and the environment areprevented. The energy recovery cylinder is in this respectadvantageously designed and is operated as described above.

The present disclosure will now be presented in more detail withreference to embodiments and to the drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a first embodiment of the present disclosure with a movedout piston rod.

FIG. 2 shows the first embodiment shown in FIG. 1 with a moved in pistonrod.

FIG. 3 shows a second embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments of a working apparatus in accordance with the presentdisclosure will now be described with reference to FIGS. 1-3, which aredrawn approximately to scale, although other relative dimensions may beused, if desired. The working apparatus in this respect has at least oneelement movable via at least one hydraulic working cylinder, with atleast one energy recovery cylinder being provided for recovering energyfrom the movement of the movable element. The energy recovery cylinderin this respect has a base side filled with gas and thus itself servesas an energy store for the energy recovery from the movement of themovable element. On a movement of the piston rod of the energy recoverycylinder, the pressurized gas stored at the base side is compressed inthis process. The energy hereby stored is then available again on anupward movement of the piston rod to support the hydraulic workingcylinder.

If an energy recovery cylinder in accordance with the present disclosureis in a loaded state, it stores large amounts of internal energy. If adefect occurs for any reason at the bearing points or at other bearingparts of the energy recovery cylinder or at the equipment in this state,the stored energy could be released in an uncontrolled manner withoutfurther security. The present disclosure now prevents this stored energyfrom moving out the piston rod of the energy recovery cylinder at anuncontrolled speed and causing damage to the energy recovery cylinder,to the working apparatus or to the environment.

The two embodiments of the present disclosure shown in FIGS. 1 to 3 arein this respect based on an energy recovery cylinder having a piston rod1 which is arranged movably in a cylinder jacket 2. The base side 4 ofthe cylinder jacket is in this respect filled with gas. Furthermore, thepiston rod 1 is made hollow and open toward the base side so that theinterior 5 of the piston rod 1 is likewise filled with gas.

The recovery cylinder in accordance with the present disclosure is inthis respect a two-sided cylinder so that an annular space 6 isfurthermore arranged between the piston rod 1 and the cylinder jacket 2.In this respect, a stuffing box 3 is provided which seals the piston rod1 toward the cylinder jacket 2 and a piston seal 7 is provided whichseals the annular space 6 toward the base side 4.

In the first embodiment of the present disclosure shown in FIGS. 1 and2, the annular space 6 is filled with a non-compressible medium, forexample hydraulic oil. In this respect, the annular space 6 is incommunication with an external container 9 via a flow restrictionelement 8. If the pressurized energy recovery cylinder can expand in anuncontrolled manner, e.g. due to a defect in the bearing points, themedium located in the annular space 6 has to flow through the flowrestriction element into the external container 9. It is hereby nolonger possible for the cylinder to expand in an uncontrolled manner.

The flow restriction element advantageously has a restrictor, adiaphragm or a valve unit. In this respect, the flow speed canadvantageously be set by the flow restriction element. The valve unitcan in this respect in particular be a flow control valve or a burstpipe protection.

FIG. 1 in this respect shows the energy recovery cylinder in accordancewith the present disclosure with a moved out piston rod 1 and thus witha filled additional container 9. FIG. 2 shows the energy recoverycylinder in accordance with the present disclosure with a moved inpiston rod 1 and thus with a partly emptied additional container 9.

In the second embodiment shown in FIG. 3, the annular space 6 is, incontrast, filled with gas and is in communication with the base side 4via the flow restriction element 10. The gas is hereby restricted on theoverflow between the annular space 6 and the base side 4 so that anuncontrolled moving out of the piston rod 1 is likewise prevented. Inthis respect, a restrictor 10 is advantageously used as the flowrestriction element. A check valve 11 is advantageously providedparallel hereto and allows a free flow of the gas from the base side 4into the annular space 6.

The present disclosure thus ensures a controlled expansion or moving outof an energy recovery cylinder under high pressure when it is no longermechanically secured due to a defect of a bearing part.

While only FIG. 1 shows the working apparatus 21 and working cylinder23, such components may also be included in FIGS. 2 and 3.

1. A working apparatus, comprising: an element movable via at least onehydraulic working cylinder, wherein at least one energy recoverycylinder is provided for recovering energy from a movement of themovable element, said energy recovering cylinder being filled with gasat a base side and having an annular space filled with a medium, whereina flow restriction element is provided which restricts a flow of themedium out of the annular space on a sudden moving out of a piston rod.2. A working apparatus in accordance with claim 1, wherein the flowrestriction element is in communication with an external reservoir intowhich the medium flows on a moving out of the piston rod.
 3. A workingapparatus in accordance with claim 1, wherein the medium is notcompressible.
 4. A working apparatus in accordance with claim 1, whereinthe flow restriction element is a restrictor, a diaphragm and/or a valveunit.
 5. A working apparatus in accordance with claim 1, wherein theannular space is in communication with the base side of the energyrecovery cylinder filled with gas via the flow restriction element.
 6. Aworking apparatus in accordance with claim 5, wherein the flowrestriction element is a restrictor.
 7. A working apparatus inaccordance with claim 6, wherein a check valve is arranged parallel tothe restrictor.
 8. A working apparatus in accordance with claim 1,wherein the energy recovery cylinder has a hollow piston rod.
 9. Aworking apparatus in accordance with claim 1, wherein the flowrestriction element is a restrictor, a diaphragm and/or a valve unithaving an adjustable volume, wherein the working apparatus is anexcavator or a machine for material handling.
 10. A method of operatinga working apparatus, having an element movable via at least onehydraulic working cylinder, wherein at least one energy recoverycylinder is provided for recovering energy from a movement of themovable element, said energy recovery cylinder being filled with gas ata base side and having an annular space filled with a medium,comprising: restricting a flow of the medium out of the annular spaceduring an unwanted moving out of a piston rod.
 11. A working apparatus,comprising: at least one hydraulic working cylinder; an element movablevia the at least one hydraulic working cylinder; at least one energyrecovery cylinder movable in parallel with the hydraulic workingcylinder on a movement of the movable element, the energy recoverycylinder having a cylinder jacket and a piston rod for recovering energyfrom movement of the movable element, said energy recovering cylinderfilled with gas at a base side and having an annular space filled with ahydraulic medium; and a flow restriction element which restricts a flowof the medium out of the annular space on a sudden moving out of thepiston rod, the flow restriction element positioned exterior to thepiston rod and the cylinder jacket.
 12. A working apparatus inaccordance with claim 11, wherein the energy recovery cylinder iscoupled to the element.
 13. A working apparatus in accordance with claim12, wherein the flow restriction element is a restrictor, a diaphragmand/or a valve unit.
 14. A working apparatus in accordance with claim13, wherein the annular space is in communication with the base side ofthe energy recovery cylinder filled with gas via the flow restrictionelement.
 15. A working apparatus in accordance with claim 14, wherein acheck valve is arranged parallel to the restrictor.